Multi-speed planetary transmission

ABSTRACT

A multi-speed transmission including a plurality of planetary gearsets and a plurality of selective couplers to achieve at least nine forward speed ratios is disclosed. The plurality of planetary gearsets may include a first planetary gearset, a second planetary gearset, a third planetary gearset, and a fourth planetary gearset. The plurality of selective couplers may include a number of clutches and a number of brakes. The multi-speed transmission may have four planetary gearsets and six selective couplers. The six selective couplers may include three clutches and three brakes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of prior application Ser. No. 15/477,165, filed Apr. 3, 2017, titled MULTI-SPEED PLANETARY TRANSMISSION, Attorney Docket No. AT-P16009-US-ORD-01, which claims the benefit of U.S. Provisional Application Ser. No. 62/400,901, filed Sep. 28, 2016, titled MULTI-SPEED PLANETARY TRANSMISSION, Attorney Docket No. AT-P16009USP1, the entire disclosure of both of which are expressly incorporated by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to a multi-speed transmission and in particular to a multi-speed transmission including a plurality of planetary gearsets and a plurality of selective couplers to achieve at least nine forward speed ratios and at least one reverse speed ratio.

BACKGROUND OF THE DISCLOSURE

Multi-speed transmissions use a plurality of planetary gearsets, selective couplers, interconnectors, and additional elements to achieve a plurality of forward and reverse speed ratios. Exemplary multi-speed transmissions are disclosed in US Published Patent Application No. 2016/0047440, Ser. No. 14/457,592, titled MULTI-SPEED TRANSMISSION, filed Aug. 12, 2014, the entire disclosure of which is expressly incorporated by reference herein.

SUMMARY

The present disclosure provides a multi-speed transmission including a plurality of planetary gearsets and a plurality of selective couplers to achieve at least nine forward speed ratios. The plurality of planetary gearsets may include a first planetary gearset, a second planetary gearset, a third planetary gearset, and a fourth planetary gearset. The plurality of selective couplers may include a number of clutches and a number of brakes. In one example, the present disclosure provides a multi-speed transmission having four planetary gearsets and six selective couplers. The six selective couplers may include three clutches and three brakes.

In some instances throughout this disclosure and in the claims, numeric terminology, such as first, second, third, and fourth, is used in reference to various gearsets, gears, gearset components, interconnectors, selective couplers, and other components. Such use is not intended to denote an ordering of the components. Rather, numeric terminology is used to assist the reader in identifying the component being referenced and should not be narrowly interpreted as providing a specific order of components. For example, a first planetary gearset identified in the drawings may support any one of the plurality of planetary gearsets recited in the claims, including the first planetary gearset, the second planetary gearset, the third planetary gearset, and the fourth planetary gearset, depending on the language of the claims.

According to an exemplary embodiment of the present disclosure, a transmission is provided. The transmission comprises at least one stationary member, an input member, a plurality of planetary gearsets operatively coupled to the input member, a plurality of selective couplers operatively coupled to the plurality of planetary gearsets, and an output member operatively coupled to the input member through the plurality of planetary gearsets. Each planetary gearset of the plurality of planetary gearsets includes a sun gear, a plurality of planet gears operatively coupled to the sun gear, a planet carrier operatively coupled to the plurality of planet gears, and a ring gear operatively coupled to the plurality of planet gears. The plurality of planetary gearsets includes a first planetary gearset, a second planetary gearset, a third planetary gearset, and a fourth planetary gearset. Each of the plurality of selective couplers has an engaged configuration and a disengaged configuration. The plurality of selective couplers includes a first number of clutches and a second number of brakes. The input member is fixedly coupled to the ring gear of the first planetary gearset and the ring gear of the second planetary gearset. The output member is fixedly coupled to the planet carrier of the fourth planetary gearset. The plurality of selective couplers are selectively engaged in a plurality of combinations to establish at least nine forward speed ratios and at least one reverse speed ratio between the input member and the out member. Each of the plurality of combinations has at least three of the plurality of selective couplers engaged.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of exemplary embodiments taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagrammatic view of an exemplary multi-speed transmission including four planetary gearsets and six selective couplers; and

FIG. 2 is a truth table illustrating the selective engagement of the six selective couplers of FIG. 1 to provide ten forward gear or speed ratios and a reverse gear or speed ratio of the multi-speed transmission of FIG. 1.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an exemplary embodiment of the invention and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the present disclosure, reference is now made to the embodiment illustrated in the drawings, which is described below. The embodiments disclosed below are not intended to be exhaustive or limit the present disclosure to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize its teachings. Therefore, no limitation of the scope of the present disclosure is thereby intended. Corresponding reference characters indicate corresponding parts throughout the several views.

In the disclosed transmission embodiment, selective couplers are disclosed. A selective coupler is a device which may be actuated to fixedly couple two or more components together. A selective coupler fixedly couples two or more components to rotate together as a unit when the selective coupler is in an engaged configuration. Further, the two or more components may be rotatable relative to each other when the selective coupler is in a disengaged configuration. The terms “couples”, “coupled”, “coupler” and variations thereof are used to include both arrangements wherein the two or more components are in direct physical contact and arrangements wherein the two or more components are not in direct contact with each other (e.g., the components are “coupled” via at least a third component), but yet still cooperate or interact with each other.

A first exemplary selective coupler is a clutch. A clutch couples two or more rotating components to one another so that the two or more rotating components rotate together as a unit in an engaged configuration and permits relative rotation between the two or more rotating components in the disengaged position. Exemplary clutches may be shiftable friction-locked multi-disk clutches, shiftable form-locking claw or conical clutches, wet clutches, or any other known form of a clutch.

A second exemplary selective coupler is a brake. A brake couples one or more rotatable components to a stationary component to hold the one or more rotatable components stationary relative to the stationary component in the engaged configuration and permits rotation of the one or more components relative to the stationary component in the disengaged configuration. Exemplary brakes may be configured as shiftable-friction-locked disk brakes, shiftable friction-locked band brakes, shiftable form-locking claw or conical brakes, or any other known form of a brake.

Selective couplers may be actively controlled devices or passive devices. Exemplary actively controlled devices include hydraulically actuated clutch or brake elements and electrically actuated clutch or brake elements. Additional details regarding systems and methods for controlling selective couplers are disclosed in the above-incorporated US Published Patent Application No. 2016/0047440.

In addition to coupling through selective couplers, various components of the disclosed transmission embodiments may be fixedly coupled together continuously throughout the operation of the disclosed transmissions. Components may be fixedly coupled together either permanently or removably. Components may be fixedly coupled together through spline connections, press fitting, fasteners, welding, machined or formed functional portions of a unitary piece, or other suitable methods of connecting components.

The disclosed transmission embodiments include a plurality of planetary gearsets. Each planetary gearset includes at least four components: a sun gear; a ring gear; a plurality of planet gears; and a carrier that is rotatably coupled to and carries the planet gears. In the case of a simple planetary gearset, the teeth of the sun gear are intermeshed with the teeth of the planet gears which are in turn intermeshed with the teeth of the ring gear. Each of these components may also be referred to as a gearset component. It will be apparent to one of skill in the art that some planetary gearsets may include further components than those explicitly identified. For example, one or more of the planetary gearsets may include two sets of planet gears. A first set of planet gears may intermesh with the sun gear while the second set of planet gears intermesh with the first set of planet gears and the ring gear. Both sets of planet gears are carried by the planet carrier.

One or more rotating components, such as shafts, drums, and other components, may be collectively referred to as an interconnector when the one or more components are fixedly coupled together. Interconnectors may further be fixedly coupled to one or more gearset components and/or one or more selective couplers.

An input member of the disclosed transmission embodiments is rotated by a prime mover. Exemplary prime movers include internal combustion engines, electric motors, hybrid power systems, and other suitable power systems. In one embodiment, the prime mover indirectly rotates the input member through a clutch and/or a torque converter. An output member of the disclosed transmission embodiments provides rotational power to one or more working components. Exemplary working components include one or more drive wheels of a motor vehicle, a power take-off shaft, and other suitable devices. The output member is rotated based on the interconnections of the gearset components and the selective couplers of the transmission. By changing the interconnections of the gearset components and the selective couplers, a rotation speed of the output member may be varied from a rotation speed of the input member.

The disclosed transmission embodiments are capable of transferring torque from the input member to the output member and rotating the output member in at least nine forward gear or speed ratios relative to the input member, illustratively ten forward gear or speed ratios, and one reverse gear or speed ratio wherein the rotation direction of the output member is reversed relative to its rotation direction for the at least nine forward ratios. Exemplary gear ratios that may be obtained using the embodiments of the present disclosure are disclosed herein. Of course, other gear ratios are achievable depending on the characteristics of the gearsets utilized. Exemplary characteristics include respective gear diameters, the number of gear teeth, and the configurations of the various gears.

FIG. 1 is a diagrammatic representation of a multi-speed transmission 100. Multi-speed transmission 100 includes an input member 102 and an output member 104. Each of input member 102 and output member 104 is rotatable relative to at least one stationary member 106. An exemplary input member 102 is an input shaft or other suitable rotatable component. An exemplary output member 104 is an output shaft or other suitable rotatable component. An exemplary stationary member 106 is a housing of multi-speed transmission 100. The housing may include several components coupled together.

Multi-speed transmission 100 includes a plurality of planetary gearsets, illustratively a first planetary gearset 108, a second planetary gearset 110, a third planetary gearset 112, and a fourth planetary gearset 114. In one embodiment, additional planetary gearsets may be included. Further, although first planetary gearset 108, second planetary gearset 110, third planetary gearset 112, and fourth planetary gearset 114 are illustrated as simple planetary gearsets, it is contemplated that compound planetary gearsets may be included in some embodiments.

In one embodiment, multi-speed transmission 100 is arranged as illustrated in FIG. 1, with first planetary gearset 108 positioned between a first location or end 116 at which input member 102 enters stationary member 106 and second planetary gearset 110, second planetary gearset 110 is positioned between first planetary gearset 108 and third planetary gearset 112, third planetary gearset 112 is positioned between second planetary gearset 110 and fourth planetary gearset 114, and fourth planetary gearset 114 is positioned between third planetary gearset 112 and a second location or end 118 at which output member 104 exits stationary member 106. In alternative embodiments, first planetary gearset 108, second planetary gearset 110, third planetary gearset 112, and fourth planetary gearset 114 are arranged in any order relative to location 116 and location 118. In the illustrated embodiment of FIG. 1, each of first planetary gearset 108, second planetary gearset 110, third planetary gearset 112, and fourth planetary gearset 114 are axially aligned. In one example, input member 102 and output member 104 are also axially aligned with first planetary gearset 108, second planetary gearset 110, third planetary gearset 112, and fourth planetary gearset 114. In alternative embodiments, one or more of input member 102, output member 104, first planetary gearset 108, second planetary gearset 110, third planetary gearset 112, and fourth planetary gearset 114 are offset and not axially aligned with the remainder.

First planetary gearset 108 includes a sun gear 120, a planet carrier 122 supporting a plurality of planet gears 124, and a ring gear 126. Second planetary gearset 110 includes a sun gear 130, a planet carrier 132 supporting a plurality of planet gears 134, and a ring gear 136. Third planetary gearset 112 includes a sun gear 140, a planet carrier 142 supporting a plurality of planet gears 144, and a ring gear 146. Fourth planetary gearset 114 includes a sun gear 150, a planet carrier 152 supporting a plurality of planet gears 154, and a ring gear 156.

Multi-speed transmission 100 further includes a plurality of selective couplers, illustratively a first selective coupler 162, a second selective coupler 164, a third selective coupler 166, a fourth selective coupler 168, a fifth selective coupler 170, and a sixth selective coupler 172. In the illustrated embodiment, first selective coupler 162, second selective coupler 164, and third selective coupler 166 are brakes and fourth selective coupler 168, fifth selective coupler 170, and sixth selective coupler 172 are clutches. The axial locations of the clutches and brakes relative to the plurality of planetary gearsets may be altered from the illustrated axial locations.

Multi-speed transmission 100 includes several components that are illustratively shown as being fixedly coupled together. Input member 102 is fixedly coupled to ring gear 126 of first planetary gearset 108 and ring gear 136 of second planetary gearset 110. Output member 104 is fixedly coupled to planet carrier 152 of fourth planetary gearset 114 and fourth selective coupler 168. Sun gear 120 of first planetary gearset 108, sun gear 130 of second planetary gearset 110, sun gear 140 of third planetary gearset 112, and first selective coupler 162 are fixedly coupled together. Ring gear 146 of third planetary gearset 112 is fixedly coupled to sun gear 150 of fourth planetary gearset 114. Planet carrier 122 of first planetary gearset 108, fifth selective coupler 170, and sixth selective coupler 172 are fixedly coupled together. Planet carrier 132 of second planetary gearset 110 is fixedly coupled to second selective coupler 164. Ring gear 156 of fourth planetary gearset 114, fourth selective coupler 168, and fifth selective coupler 170 are fixedly coupled together. Planet carrier 142 of third planetary gearset 112, third selective coupler 166, and sixth selective coupler 172 are fixedly coupled together.

Multi-speed transmission 100 may be described as having eight interconnectors. Input member 102 is a first interconnector that both provides input torque to multi-speed transmission 100 and fixedly couples ring gear 126 of first planetary gearset 108 to ring gear 136 of second planetary gearset 110. Output member 104 is a second interconnector that both provides output torque from multi-speed transmission 100 and fixedly couples planet carrier 152 of fourth planetary gearset 114 to fourth selective coupler 168. A third interconnector 180 fixedly couples sun gear 120 of first planetary gearset 108, sun gear 130 of second planetary gearset 110, sun gear 140 of third planetary gearset 112, and first selective coupler 162 together. A fourth interconnector 182 fixedly couples ring gear 146 of third planetary gearset 112 and sun gear 150 of fourth planetary gearset 114 together. A fifth interconnector 184 fixedly couples planet carrier 122 of first planetary gearset 108, fifth selective coupler 170, and sixth selective coupler 172 together. A sixth interconnector 186 fixedly couples planet carrier 132 of second planetary gearset 110 to second selective coupler 164. A seventh interconnector 188 fixedly couples ring gear 156 of fourth planetary gearset 114, fourth selective coupler 168, and fifth selective coupler 170 together. An eighth interconnector 190 fixedly couples planet carrier 142 of third planetary gearset 112, third selective coupler 166, and sixth selective coupler 172 together.

Multi-speed transmission 100 further includes several components that are illustratively shown as being selectively coupled together through selective couplers. First selective coupler 162, when engaged, fixedly couples sun gear 120 of first planetary gearset 108, sun gear 130 of second planetary gearset 110, and sun gear 140 of third planetary gearset 112 to stationary member 106. When first selective coupler 162 is disengaged, sun gear 120 of first planetary gearset 108, sun gear 130 of second planetary gearset 110, and sun gear 140 of third planetary gearset 112 may rotate relative to stationary member 106.

Second selective coupler 164, when engaged, fixedly couples planet carrier 132 of second planetary gearset 110 to stationary member 106. When second selective coupler 164 is disengaged, planet carrier 132 of second planetary gearset 110 may rotate relative to stationary member 106.

Third selective coupler 166, when engaged, fixedly couples planet carrier 142 of third planetary gearset 112 to stationary member 106. When third selective coupler 166 is disengaged, planet carrier 142 of third planetary gearset 112 may rotate relative to stationary member 106.

Fourth selective coupler 168, when engaged, fixedly couples ring gear 156 of fourth planetary gearset 114 to planet carrier 152 of fourth planetary gearset 114. Thus, when fourth selective coupler 168 is engaged, the planet carrier 152 of fourth planetary gearset 114 is locked together with the ring gear 156 of the fourth planetary gearset 114. When fourth selective coupler 168 is disengaged, ring gear 156 of fourth planetary gearset 114 may rotate relative to planet carrier 152 of fourth planetary gearset 114.

As mentioned, when fourth selective coupler 168 is engaged, planet carrier 152 of fourth planetary gearset 114 and ring gear 156 of fourth planetary gearset 114 are locked together. Hence, sun gear 150, planet carrier 152, and ring gear 156 of fourth planetary gearset 114 all rotate together as a single unit. The same effect may be realized by coupling any two of sun gear 150, planet carrier 152, and ring gear 156 together. In one example, fourth selective coupler 168 is fixedly coupled to ring gear 156 of fourth planetary gearset 114 and sun gear 150 of fourth planetary gearset 114. In this example, when fourth selective coupler 168 is engaged, ring gear 156 of fourth planetary gearset 114 and sun gear 150 of fourth planetary gearset 114 are locked together resulting in all of sun gear 150, planet carrier 152, and ring gear 156 of fourth planetary gearset 114 rotating together as a single unit. In another example, fourth selective coupler 168 is fixedly coupled to planet carrier 152 of fourth planetary gearset 114 and sun gear 150 of fourth planetary gearset 114. In this example, when fourth selective coupler 168 is engaged, planet carrier 152 of fourth planetary gearset 114 and sun gear 150 of fourth planetary gearset 114 are locked together resulting in all of sun gear 150, planet carrier 152, and ring gear 156 of fourth planetary gearset 114 rotating together as a single unit.

Fifth selective coupler 170, when engaged, fixedly couples planet carrier 122 of first planetary gearset 108 to ring gear 156 of fourth planetary gearset 114. When fifth selective coupler 170 is disengaged, planet carrier 122 of first planetary gearset 108 may rotate relative to ring gear 156 of fourth planetary gearset 114.

Sixth selective coupler 172, when engaged, fixedly couples planet carrier 122 of first planetary gearset 108 to planet carrier 142 of third planetary gearset 112. When sixth selective coupler 172 is disengaged, planet carrier 122 of first planetary gearset 108 may rotate relative to planet carrier 142 of third planetary gearset 112.

By engaging various combinations of first selective coupler 162, second selective coupler 164, third selective coupler 166, fourth selective coupler 168, fifth selective coupler 170, and sixth selective coupler 172, additional components of multi-speed transmission 100 may be fixedly coupled together.

The plurality of planetary gearsets and the plurality of selective couplers of multi-speed transmission 100 may be interconnected in various arrangements to provide torque from input member 102 to output member 104 in at least nine forward gear or speed ratios and one reverse gear or speed ratio. Referring to FIG. 2, an exemplary truth table 200 is shown that provides the state of each of first selective coupler 162, second selective coupler 164, third selective coupler 166, fourth selective coupler 168, fifth selective coupler 170, and sixth selective coupler 172 for ten different forward gear or speed ratios and one reverse gear or speed ratio. Each row corresponds to a given interconnection arrangement for transmission 100. The first column provides the gear range (reverse and 1^(st)-10^(th) forward gears). The second column provides the gear ratio between the input member 102 and the output member 104. The third column provides the gear step. The six rightmost columns illustrate which ones of the selective couplers 162-172 are engaged (“1” indicates engaged) and which ones of selective couplers 162-172 are disengaged (“(blank)” indicates disengaged). FIG. 2 is only one example of any number of truth tables possible for achieving at least nine forward ratios and one reverse ratio.

In the example of FIG. 2, the illustrated reverse ratio (Rev) is achieved by having second selective coupler 164, fourth selective coupler 168, and fifth selective coupler 170 in an engaged configuration and first selective coupler 162, third selective coupler 166, and sixth selective coupler 172 in a disengaged configuration.

In one embodiment, to place multi-speed transmission 100 in neutral (Neu), all of first selective coupler 162, second selective coupler 164, third selective coupler 166, fourth selective coupler 168, fifth selective coupler 170, and sixth selective coupler 172 are in the disengaged configuration. One or more of first selective coupler 162, second selective coupler 164, third selective coupler 166, fourth selective coupler 168, fifth selective coupler 170, and sixth selective coupler 172 may remain engaged in neutral (Neu) as long as the combination of first selective coupler 162, second selective coupler 164, third selective coupler 166, fourth selective coupler 168, fifth selective coupler 170, and sixth selective coupler 172 does not transmit torque from input member 102 to output member 104.

A first forward ratio (shown as 1st) in truth table 200 of FIG. 2 is achieved by having second selective coupler 164, fifth selective coupler 170, and sixth selective coupler 172 in an engaged configuration and first selective coupler 162, third selective coupler 166, and fourth selective coupler 168 in a disengaged configuration.

A second or subsequent forward ratio (shown as 2nd) in truth table 200 of FIG. 2 is achieved by having second selective coupler 164, third selective coupler 166, and fifth selective coupler 170 in an engaged configuration and first selective coupler 162, fourth selective coupler 168, and sixth selective coupler 172 in a disengaged configuration. Therefore, when transitioning between the first forward ratio and the second forward ratio, sixth selective coupler 172 is placed in the disengaged configuration and third selective coupler 166 is placed in the engaged configuration.

A third or subsequent forward ratio (shown as 3rd) in truth table 200 of FIG. 2 is achieved by having third selective coupler 166, fifth selective coupler 170, and sixth selective coupler 172 in an engaged configuration and first selective coupler 162, second selective coupler 164, and fourth selective coupler 168 in a disengaged configuration. Therefore, when transitioning between the second forward ratio and the third forward ratio, second selective coupler 164 is placed in the disengaged configuration and sixth selective coupler 172 is placed in the engaged configuration.

A fourth or subsequent forward ratio (shown as 4th) in truth table 200 of FIG. 2 is achieved by having third selective coupler 166, fourth selective coupler 168, and fifth selective coupler 170 in an engaged configuration and first selective coupler 162, second selective coupler 164, and sixth selective coupler 172 in a disengaged configuration. Therefore, when transitioning between the third forward ratio and the fourth forward ratio, sixth selective coupler 172 is placed in the disengaged configuration and fourth selective coupler 168 is placed in the engaged configuration.

A fifth or subsequent forward ratio (shown as 5th) in truth table 200 of FIG. 2 is achieved by having first selective coupler 162, third selective coupler 166, and fifth selective coupler 170 in an engaged configuration and second selective coupler 164, fourth selective coupler 168, and sixth selective coupler 172 in a disengaged configuration. Therefore, when transitioning between the fourth forward ratio and the fifth forward ratio, fourth selective coupler 168 is placed in the disengaged configuration and first selective coupler 162 is placed in the engaged configuration.

A sixth or subsequent forward ratio (shown as 6th) in truth table 200 of FIG. 2 is achieved by having first selective coupler 162, fourth selective coupler 168, and fifth selective coupler 170 in an engaged configuration and second selective coupler 164, third selective coupler 166, and sixth selective coupler 172 in a disengaged configuration. Therefore, when transitioning between the fifth forward ratio and the sixth forward ratio, third selective coupler 166 is placed in the disengaged configuration and fourth selective coupler 168 is placed in the engaged configuration.

A seventh or subsequent forward ratio (shown as 7th) in truth table 200 of FIG. 2 is achieved by having fourth selective coupler 168, fifth selective coupler 170, and sixth selective coupler 172 in an engaged configuration and first selective coupler 162, second selective coupler 164, third selective coupler 166 in a disengaged configuration. Therefore, when transitioning between the sixth forward ratio and the seventh forward ratio, first selective coupler 162 is placed in the disengaged configuration and sixth selective coupler 172 is placed in the engaged configuration.

An eighth or subsequent forward ratio (shown as 8th) in truth table 200 of FIG. 2 is achieved by having third selective coupler 166, fourth selective coupler 168, and sixth selective coupler 172 in an engaged configuration and first selective coupler 162, second selective coupler 164, and fifth selective coupler 170 in a disengaged configuration. Therefore, when transitioning between the seventh forward ratio and the eighth forward ratio, fifth selective coupler 170 is placed in the disengaged configuration and third selective coupler 166 is placed in the engaged configuration.

A ninth or subsequent forward ratio (shown as 9th) in truth table 200 of FIG. 2 is achieved by having second selective coupler 164, fourth selective coupler 168, and sixth selective coupler 172 in an engaged configuration and first selective coupler 162, third selective coupler 166, and fifth selective coupler 170 in a disengaged configuration. Therefore, when transitioning between the eighth forward ratio and the ninth forward ratio, third selective coupler 166 is placed in the disengaged configuration and second selective coupler 164 is placed in the engaged configuration.

A tenth or subsequent forward ratio (shown as 10th) in truth table 200 of FIG. 2 is achieved by having second selective coupler 164, third selective coupler 166, and fourth selective coupler 168 in an engaged configuration and first selective coupler 162, fifth selective coupler 170, and sixth selective coupler 172 in a disengaged configuration. Therefore, when transitioning between the ninth forward ratio and the tenth forward ratio, sixth selective coupler 172 is placed in the disengaged configuration and third selective coupler 166 is placed in the engaged configuration.

The present disclosure contemplates that downshifts follow the reverse sequence of the corresponding upshift (as described above). Further, several power-on skip-shifts that are single-transition are possible (e.g. from 1^(st) up to 3^(rd), from 3^(rd) down to 1^(st), from 3^(rd) up to 5^(th), and from 5^(th) down to 3rd).

In the illustrated embodiment, various combinations of three of the available selective couplers are engaged for each of the illustrated forward speed ratios and reverse speed ratios. Additional forward speed ratios and reverse speed ratios are possible based on other combinations of engaged selective couplers. Although in the illustrated embodiment, each forward speed ratio and reverse speed ratio has three of the available selective couplers engaged, it is contemplated that less than three and more than three selective couplers may be engaged at the same time.

While this invention has been described as having exemplary designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims. 

What is claimed is:
 1. A transmission comprising: at least one stationary member; an input member; a plurality of planetary gearsets operatively coupled to the input member, each planetary gearset of the plurality of planetary gearsets including a sun gear, a plurality of planet gears operatively coupled to the sun gear, a planet carrier operatively coupled to the plurality of planet gears, and a ring gear operatively coupled to the plurality of planet gears, the plurality of planetary gearsets including a first planetary gearset, a second planetary gearset, a third planetary gearset, and a fourth planetary gearset; a plurality of selective couplers operatively coupled to the plurality of planetary gearsets, each of the plurality of selective couplers having an engaged configuration and a disengaged configuration, the plurality of selective couplers including a first number of clutches and a second number of brakes; and an output member operatively coupled to the input member through the plurality of planetary gearsets, wherein the input member is fixedly coupled to the ring gear of the first planetary gearset and the ring gear of the second planetary gearset, the output member is fixedly coupled to the planet carrier of the fourth planetary gearset, wherein the plurality of selective couplers are selectively engaged in a plurality of combinations to establish at least nine forward speed ratios and at least one reverse speed ratio between the input member and the output member, each of the plurality of combinations having at least three of the plurality of selective couplers engaged.
 2. The transmission of claim 1, wherein a first portion of the first planetary gearset is fixedly coupled to a second portion of the second planetary gearset and to a third portion of the third planetary gearset.
 3. The transmission of claim 2, wherein the first portion of the first planetary gearset is the sun gear of the first planetary gearset, the second portion of the second planetary gearset is the sun gear of the second planetary gearset, and the third portion of the third planetary gearset is the sun gear of the third planetary gearset.
 4. The transmission of claim 1, wherein the plurality of selective couplers includes a first clutch, a second clutch, a third clutch, a first brake fixedly coupled to the at least one stationary member, a second brake fixedly coupled to the at least one stationary member, and a third brake fixedly coupled to the at least one stationary member.
 5. The transmission of claim 4, further comprising: a first interconnector which fixedly couples the sun gear of the first planetary gearset, the sun gear of the second planetary gearset, and the sun gear of the third planetary gearset together; and a second interconnector which fixedly couples the ring gear of the third planetary gearset to the sun gear of the fourth planetary gearset.
 6. The transmission of claim 5, wherein the first brake, when engaged, fixedly couples the sun gear of the first planetary gearset, the sun gear of the second planetary gearset, and the sun gear of the third planetary gearset to the at least one stationary member; the second brake, when engaged, fixedly couples the planet carrier of the second planetary gearset to the at least one stationary member; the third brake, when engaged, fixedly couples the planet carrier of the third planetary gearset to the at least one stationary member; the first clutch, when engaged, fixedly couples a first one of the sun gear of the fourth planetary gearset, the planet carrier of the fourth planetary gearset, and the ring gear of the fourth planetary gearset to a second one of the sun gear of the fourth planetary gearset, the planet carrier of the fourth planetary gearset, and the ring gear of the fourth planetary gearset; the second clutch, when engaged, fixedly couples the planet carrier of the first planetary gearset to the ring gear of the fourth planetary gearset; and the third clutch, when engaged, fixedly couples the planet carrier of the third planetary gearset to the planet carrier of the first planetary gearset.
 7. The transmission of claim 1, wherein the at least one stationary member includes a housing, the housing having a first end and a second end, wherein the input member is accessible proximate the first end of the housing; the output member is accessible proximate the second end of the housing; the first planetary gearset is positioned between the first end of the housing and the second planetary gearset; the second planetary gearset is positioned between the first planetary gearset and the third planetary gearset; the third planetary gearset is positioned between the second planetary gearset and the fourth planetary gearset; and the fourth planetary gearset is positioned between the third planetary gearset and the second end of the housing. 